This invention relates to radar and communication systems. More particularly, the invention relates to a switchable microwave fluidic polarizer for changing the polarization of signals associated with an antenna.
The trend toward lower cost and lighter weight active array antennas for radar systems has caused the focus on array architecture to evolve from developing brick and tile subarray assemblies toward thinner and lighter multilayer printed circuit board (PCB) panel subarray assemblies. In some antenna systems, monolithic microwave integrated circuit (MMIC) devices that can make up the transmit/receive (TR) modules are now generally mounted directly to the panel subarray.
A linearly polarized wave may be converted to a circularly polarized wave by means of a panel which provides a 90 degree difference in transmission phase between two crossed linear components. The panel is generally a meander line plate which is a dielectric slab with etched copper meander lines. The electric field of the wave incident to the panel is separated into two equal orthogonal components parallel (E-parallel) and perpendicular (E-perpendicular) to the meander line axis. The E-parallel components are delayed due to the inductive effective, and the E-perpendicular component is advanced due to the capacitive effect of the grating structure of the meander-line polarizers.
The meander-line polarizer has the advantages of broadband frequency operation with low insertion loss and ease of manufacturing. In the past, meander-line polarizers have been used to effect linear-to-circular polarization conversion and to cause a 90 degree rotation of a linearly polarized signal. The meander-line polarizer would then consist of several printed circuit sheets with etched-copper meander lines. The challenge for the future is adding such functionality in front of an active array antenna that is switchable and reconfigurable.